1. Technical Field
The present invention relates to an apparatus, method, and system for transporting heat.
2. Description of Related Art
Refrigeration is the process of removing heat from an enclosed space or from a substance for the purpose of lowering the temperature. Refrigeration systems are important to many aspects of modern life. Common uses for refrigeration systems include refrigerators for preserving food, air conditioning systems for controlling the interior climate of homes and offices, systems for cooling engines such as for automobiles, and devices for cooling electronics such that the electronics performs optimally.
Typically, cooling systems are mechanical systems, such as, for example, simple fans for pulling heated air away from an area to be cooled, as used in many computers, or vapor-compression cooling as used for many household refrigerators and air-conditioning systems. In vapor-compression type cooling, a gas coolant, such as freon, is first compressed, usually by a piston, and then pushed through a tube into the condenser. In the condenser, the winding tube containing the vapor is passed through either circulating air or a bath of water, which removes some of the heat energy of the compressed gas. The cooled vapor is passed through an expansion valve to an area of much lower pressure; as the vapor expands, it draws the energy of its expansion from its surroundings or the medium in contact with it. Evaporators may directly cool a space by letting the vapor come into contact with the area to be chilled, or they may act indirectlyxe2x80x94i.e., by cooling a secondary medium such as water. In most domestic refrigerators, the coil containing the evaporator directly contacts the air in the food compartment. At the end of the process, the hot gas is drawn toward the compressor.
In addition to mechanical coolers, solid state devices, such as thermoelectric coolers, are also utilized to cool devices. Due to current technological and economic constraints, these coolers are typically used only for electronics.
However, one problem with all current coolers is the inability of the system to efficiently transport and reject heat at distant locations. Usually, the heat is rejected to a fluidic system (such as air or circulating water), as discussed above, through heat fins, heat pipers, or heat exchangers. These systems have many limitations such as fluid leakages, acoustic noise, gravity dependent performance, and finite transport distances. Therefore, it would be desirable to have a system of heat transport that allows heat to be more efficiently transported over long distances and rejected at more distant locations than is currently possible with existing technology.
The present invention provides an apparatus and method for transporting and rejecting heat energy. In one embodiment, the heat transporter includes a photonic microheatpipe and a source of photons. The photonic microheatpipe is a photonic crystal that shows pronounced Raman effect and is thermally coupled to a heat source. Photonic crystals disallow certain frequencies of light from being transmitted through the crystal. When a photon scatters back from phonons (lattice vibrations) in the crystal, the properties of the reflected spectrum are governed by the Raman effect. The reflected spectrum have two pronounced components: a Stock""s line and an Anti-Stokes line. The Stokes lines correspond to frequencies that are the difference between the frequency of the incident photons and that of the phonons, while the anti-Stokes lines correspond to frequencies that are sum of the frequency of the incident photons and that of the phonons. According to the present invention, the photonic crystal is selected such that the Stokes lines are suppressed while the anti-Stokes lines are not attenuated. Hence the photons reflected from the photonic crystal have frequencies (and energy) greater than the incident photons. Thus, heat energy represented as acoustic phonons is transferred into photons. The photons corresponding to the anti-Stoke lines are transmitted through the photonic microheatpipe away from the heat source to a suitable point for rejecting the heat energy.